Circulation 36,825 • Volume 17, No. 3 • Fall 2002

FDA Encourages the Reporting of Medical Device Adverse Events: Free-Hosing Hazards

Julia Marders, RN, MS

Healthcare professionals in the clinical setting are the link between warming blankets and desired patient outcomes. This article presents two events involving patient injury and the use of forced air warming devices.

Forced Air Warming

Warming blankets are commonly used medical devices for rewarming patients exposed to conditions causing hypothermia. These devices are used in perioperative and critical care units to maintain normal body temperature or treat hypothermia. A forced air warming device uses heated air to warm patients through convection. This warming system consists of 1) heater, 2) disposable blanket, and 3) hose. The hose is designed to deliver heated air from the thermostatically controlled heater to the blanket. The blanket distributes warmed air uniformly across skin surfaces and also lowers the temperature of the heated air.1

Complications of forced air warming devices have been reported when a blanket is not attached to the hose. This practice allows the warm air to blow directly onto the patient and is referred to as “free-hosing” in the clinical setting.

Patient Injury: FDA Data

The Food and Drug Administration (FDA) monitors products that have been approved for marketing. Within the FDA, the Center for Devices and Radiological Health (CDRH), receives post-market adverse event reports submitted by manufacturers, user facilities, healthcare professionals, and consumers involving death, serious injury, and product malfunctions. These reports provide information about newly emerging or recurring problems associated with medical device use. The FDA analyzes the reports to determine the safety impact on the public health and makes recommendations to manufacturers, healthcare professionals, and consumers. The following two reported events describe serious injuries that have occurred due to the practice of free hosing.

Event 1: A hypothermic, surgical patient was being warmed using a warming device. The warm air was blown onto the patient without using the blanket from the warming unit. No blanket was attached to the hose. The patient received second and third degree burns to the lower extremities.

Event 2: During surgery, the hose of a warming blanket was placed under the patient’s blankets. No blanket was attached to the hose. The patient suffered a burn to the lower leg, which lead to muscle necrosis. Eventually, the patient underwent an above the knee amputation.


Although complications are rare, misuse of warming devices may cause problems.2 Healthcare professionals can prevent or minimize patient complications associated with warming blankets and should familiarize themselves with correct operating instructions and techniques, precautions, warnings, or associated risks to specific patient populations as provided by the manufacturers’ labeling and instructions for use. Development of policy and procedures regarding forced air warming of patients can help standardize the use of these systems and improve overall patient safety in the clinical setting. Educating staff about the purpose of the blanket, potential for burns, and recognition of off-label use of warming systems may decrease the frequency and severity of complications. Promoting patient safety and minimizing patient complications are the healthcare professional’s responsibilities when using warming blankets or any medical devices.

Reporting Adverse Events

The FDA requires and encourages the submission of adverse events associated with medical devices. User facilities are required to report adverse events involving medical devices that have, or may have, caused or contributed to a death or serious injury. All who care for patients should become familiar with their facility’s procedures for reporting adverse events associated with medical devices. Adverse events, including those in which a device failed to perform as intended but did not result in a death or serious injury, may also be reported voluntarily through the FDA’s MedWatch program. Reporters may remain anonymous. However, the FDA encourages reporters to identify themselves to ensure timely and accurate follow-up on a reported event. A voluntary adverse event report can be submitted through MedWatch by calling 1-800-FDA-1088 or online at

The FDA communicates findings from post-market monitoring efforts through articles in peer reviewed clinical journals and through a device safety website: The information on the website includes Safety Alerts, Notifications, and Advisories, as well as recalls. Readers interested in receiving Safety Alerts, Public Health Advisories, and other FDA safety notices by e-mail as they are released, may subscribe to the Dev-Alert mailing list via a link on the FDA Device Safety website or by logging on to Medical device adverse event reports are available through a searchable database on the website at maude.html. The MAUDE database includes voluntary reports from June 1993 to the present, user facility reports since 1991, and manufacturer reports from August 1996 through the present. Data on this website are updated quarterly.

Recently, the FDA initiated a new way to communicate device safety information, the Patient Safety News. This news series, available through satellite broadcast networks aimed at hospitals and other healthcare facilities across the country, features information on newly approved medical devices, FDA safety notifications and product recalls, as well as patient safety issues. The website version, available at, contains the text for each broadcast of the latest edition, links for more information on each story, and a feedback mechanism to send comments to the FDA about aired broadcasts.


Healthcare professionals are an essential link to medical device safety and prevention of patient complications. Two events were presented describing severe complications resulting from improper use of warming systems. As healthcare professionals, we play a pivotal role in proper medical device use and reporting adverse events to the FDA. The FDA encourages the submission of adverse event reports involving medical devices. The information is critical to accurate identification of medical device problems and clinically desirable patient outcomes.

Ms. Marders is a nursing consultant for the Food and Drug Administration’s Center for Devices and Radiological Health.

Editor’s Note: Readers are also referred to a letter from Augustine Medical published in the Spring 2002 issue of the APSF Newsletter.


  1. Misusing forced-air hyperthermia units can burn patients. Health Devices 1999;28:229-230.
  2. Truell K, et al. Third-degree burns due to intraoperative use of a Bair Hugger warming device. Ann Thorac Surg 2000;69:1933-4.